In recent years, secondary batteries typified by lithium ion secondary batteries have been widely used as power sources for mobile electronic devices such as cellular phones and mobile personal computers. In addition, electric vehicles and hybrid vehicles have developed and put into practical use, and demands for secondary batteries such as lithium ion secondary batteries have been increasing as large-size applications.
Now, as this secondary battery (hereinafter, also simply referred to as a “battery”), a battery has been widely used which is structured to have a laminated body of multiple positive electrode members and negative electrode members stacked with separators interposed therebetween, and an electrolyte solution housed in an exterior body (housing), and have a positive electrode lead terminal and a negative electrode lead terminal extracted outward from the exterior body.
As one of such batteries, a battery is known which includes a supporting member for fixing the battery on other member. It is to be noted that when the battery is fixed on other member, the supporting member is required besides the positive electrode lead terminal and the negative electrode lead terminal, because in the case of holding the battery with the use of the positive and negative electrode lead terminals, the junctions between the positive electrode lead terminal and negative electrode lead terminal, and current collectors (current-collecting foil) for connecting the positive electrode members and negative electrode members constituting the battery element are likely to be broken when external stress is applied such as vibrations.
Further, such a battery (unit battery) 60 as shown in FIG. 9 has been proposed as a battery including the supporting member (see Patent Document 1).
This battery 60 includes an exterior body 64 composed of a pair of upper and lower laminate sheets on both sides for housing a battery element 61, fixing-point forming members 65, 66 with fixing points 65a, 66a formed for use in fixing the battery 60 onto other member, and thermally welded sections 64a of peripheral sections of the pair of laminate sheets, which are thermally welded while the fixing-point forming members 65, 66 are partially placed so as to be interposed between the laminate sheets at least partially at the peripheries of the upper and lower laminate sheets on both sides. Further, a positive electrode lead terminal 67 and a negative electrode lead terminal 68 are extracted outward from sides of the exterior body 64 without the fixing-point forming members 65, 66 held.
In addition, Patent Document 1 also proposes a structure which has a fixing-point forming member 66 extracted outward through a thermally welded section 64a from a housing space 69 inside an exterior body 64 with a battery element 61 housed therein as shown in FIG. 10.
The thus configured battery (unit battery) in Patent Document 1 makes it possible to easily fix and position the battery, thereby improving workability.
Furthermore, Patent Document 2 proposes, as a battery including a supporting member, a battery (unit battery) structured to have a reinforcing core material 160 provided between a pair of core materials 154 for improving the fixing strength of a laminate case battery 150 to a unit case and improving the shape maintenance strength of a individual battery 148, as shown in FIG. 11.
However, in the case of the battery in Patent Document 1, the fixing-point forming members 65, 66 are partially placed in the housing space 69 of the battery element 61, with the battery element, in particular, the electrolyte solution in contact with the fixing-point forming members 65, 66, and there is thus a possibility that deterioration of the electrolyte solution will be accelerated. In addition, there is a possibility that the exterior body 64 will become badly sealed to cause ingress of water into the battery, and cause battery characteristics to be degraded.
In addition, in the case of the configuration in Patent Document 2, the U-shaped structure is formed from the core materials 154 and the reinforcing core material 160, and the fixing strength and the shape maintenance strength of the individual battery 148 are thus expected to be improved to some extent. However, in the case of the configuration in Patent Document 2, the U-shaped structure and the individual battery 148 are spaced at regular intervals, and the individual battery 148 is thus movable to a certain extent in the thickness direction. More specifically, when external stress is applied such as vibrations, the individual battery 148 is moved in the thickness direction, thus resulting in the problem of failing to suppress the load applied on the junctions between the positive electrode lead terminal and negative electrode lead terminal, and current collectors (current-collecting foil) for connecting the positive electrode members and negative electrode members constituting the battery element. In order to suppress the movement of the individual battery 148 in the thickness direction, it is conceivable to reduce the distance between the U-shaped structure and the individual battery 148, while the same problem as in the case of Patent Document 1 mentioned above is caused when the U-shaped structure reaches the housing space for the battery element. Therefore, there is a need to ensure the interval between the U-shaped structure and the individual battery 148 to some extent in consideration of battery characteristics and sealing properties, and there is thus a problem that the laminate case battery 150 itself undergoes an increase in size.
Patent Document 1: JP 2010-67422 A
Patent Document 2: JP 2003-68257 A